Resinous composition of epoxidized p, p&#39;-dihydroxy, diphenyldimethylmethane, a phenol-formaldehyde novolac and an alkanol-amine catalyst



United States Patent "ice RESINOUS COMPOSITION OF EPOXIDIZED p,p-

DIHYDROXY, DIPHENYLDIMETHYLMETHANE, A PHENOL-FORMALDEHYDE NOVOLAC AND ANALKANOL AMINE CATALYST Salim N. Ephraim, Forest Hills, N.Y., assignor toReichhold Chemicals, inc, White Plains, N.Y.

No Drawing. Original application Nov. 23, 1959, Ser. No. 854,589.Divided and this application Dec. 8, 1964, Ser. No. 422,881

4 Claims. (Cl. 260--831) The present application is a division of myapplication Serial No. 854,589, filed November 23, 1959, now abandoned.

This invention relates to improved resin compositions and to the methodof making the same, and to blends of phenolic resins, epoxy resins andcatalysts, wherein said resin blends have excellent shelf life at roomtemperatures and fast cure at elevated temperatures.

Blends of phenolic resins and epoxy resins have been cured heretoforewith various catalysts; however, this curing materially restricted theusefulness of the blend. For example, if the catalyst produced a rapidcure at elevated temperatures, it likewise produced a poor shelf life atroom temperatures. In such instances, a two component system of thecatalyst and the resin blend, with its attendant disadvantages, wasrequired. In contradistinction, when less reactive catalysts were usedto cure blends of phenolic resins and epoxy resins that produced systemsrelatively stable at room temperatures, such blends cured so slowly atelevated temperatures that it was substantially impossible to utilizesuch systerns from both economic and utilitarian standpoints.

Catalysts of the foregoing types have included specific amine compounds.Compositions comprising blends of the phenolic and epoxy resins curedwith certain amine catalysts produce products adaptable for a widevariety of uses; For example, such blend systems can be dis- .solved inorganic solvents and the solutions thereof find utility asthermohardenable varnishes to coat various articles, impregnate glassfabrics, etc.

An object of this invention is to provide improved resin compositionsthat combine good shelf life at room temperatures and fast cure atelevated temperatures.

Another object is to provide an improved method that comprises heatreacting blends of phenolic resins, epoxy resins, and a certain type ofamine catalyst, as described hereinbelow.

These and other objects of the invention will be apparent from thefollowing specification and appended claims.

It has been discovered that these and other objects of the invention areattained by adding hydroxyalkylated tertiary amines as catalysts toblends comprising phenolic resins and epoxy resins to obtain resinblends having long shelf life and fast curing rates at elevatedtemperatures. These hydroxylated tertiary amines may be obtained byreacting alkene oxides, such [as ethylene oxide, propylene oxide,butylene oxide, etc., with ammonia, or mono or polyamines. This group ofcompounds includes, among others, triethanol amine, N,N,N',N-tetrakis(hydroxypropyl) ethylenediamine or ethoxylated fatty acid aminesrepresented by the formula wherein R is a straight chain alkyl grouphaving between 12 and 18 carbon atoms, and wherein the sum of x and y isbetween about 2 and about 15. Compounds of the latter type arecommercially available, for example, from 3,264,369 Patented August 2,1966 the Armour Chemical Division, Chicago, under the trade nameEthomeens. Examples include Ethomeen C/ 12, wherein x and y equal 2,coconut oil being the source of the C12 alkyl group, Ethomeen 8/25,wherein x and y equal 15, soybean oil being the source of the C-18 alkylgroup, etc.

The amount of tertiary amine compound which may be added to the blend ofphenolic resin and epoxy resin ranges from about 0.5% up to about 5%,based on the combined weight of the phenolic and epoxy resins. For mostpractical purposes, however, it is preferred to use between about 1.5%and about 3.0%.

The resin blend to be catalyzed with the tertiary amine catalystconsists of conventional materials described in the prior art.

The phenolic resins, which are operative in the present invention, areof the novolac-type, which means that they are made by acidiccondensation of monoor dihydric phenols with formaldehyde. After thereaction is substantially complete, as indicated by the consumption ofthe free formaldehyde, the reaction product is stripped in vacuum toremove water and the unreacted phenol. However, in practice, it has beenfound difiicult to remove all of the unreacted phenol and, therefore,generally up to 10 weight percent (based upon phenolic resin) unreactedphenol may remain in the resin. The resulting novolac is a fusible resinhaving practically no methylol groups, but only phenolic hydroxyl groupsas the only reactive sites for further reactions. The novolac maycontain up to 10 percent by weight of unreacted phenol.

Among the monoand dihydric phenols, which may be used in producing thephenolic resins, are mononuclear monohydric phenols having at least onehydrogen formaldehyde reactive atom attached to the benzene ringthereof.

Formaldehyde-reactive hydrogen atoms of the phenols are the ortho orpara positioned hydrogen atoms of the benzene ring of the phenols and,thus, do not include the meta positioned hydrogen atoms of this ring.Examples include phenol, ortho-cresol, meta-cresol, para-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol,3,5-xylenol, para tertiary butyl phenol, amyl phenol, etc. Operativedihydric phenols include both mononuclear and polynuclear phenols, suchas resorcinol, catechol, hydroquinone, and4,4-dihydroxydiphenyldimethylmethane.

The formaldehyde is used either as an aqueous solution, as gas, or asparaformaldehyde. The mol ratio of formaldehyde to phenol depends on thedesired properties of the resulting novolac. Generally, a ratio betweenabout 0.5 and 0.85 to 1.00 is used. A ratio lower than 0.5 leads toresinsof too low molecular weight and the excess of unreacted phenolwhich has to be stripped makes the process uneconomical. A ratio ofgreater than the 0.85 usually yields insoluble and infusible masses.

'Phe epoxy resins used in the present invention are polyglycidyl othersof polyhydric phenols and are made by esterification of4,4'-d-ihydroxydiphenyldimethylmethane (Bisphenol A), with anepihalohydrin in alkaline medium. Depending upon the mol ratio ofepihalohydrin to the phenolic hydroxyl, said ratio being variablebetween about 1.0 and 10.0, resins of various molecular weights can beobtained. More specifically, it is customary to identify the resins bytheir epoxy equivalent weight; the resins can be made with an epoxyequivalent weight of about up to about 2000'. The epoxide equivalentweight is generally determined by the pyridine hydrochloride methodreported by a number of patents.

The weight ratio of phenolic resins to epoxy resins may vary from about1 to 10 to 10 to 1. Ratios ranging from about 1 to 5 to 5 to 1 werefound to be particularly advantageous. The following examples arepresented to better illustrate and describe the invention and only suchlimitations as are imposed by the appended claims are hereby intended.

PREPARATION OF RESINS To a 250 ml. three-necked round bottom flaskfitted with thermometer, agitator and reflux condenser were charged 94grams (1.0 mol) of phenol, 0.5 grams of 30% sulfuric acid, and 67 gramsof an aqueous 37% formaldehyde solution (0.82 mol). The mixture wasslowly heated to about 50-65 C. As soon as the exothermic reactionstarted, the heat was shut off. When the exotherm abated, the reactionmixture Was heated under reflux for three to four hours. Then theaqueous phase was separated and discarded, and the resinous reactionproduced was neutralized with a solution of potassium hydroxide inethanol. T hev reaction product was slowly heated in a still under mm.Hg vacuum up to 180 C. and kept at 180 C. for about one hour until nomore volatile materials were distilling off. The novolac thus producedwas poured into a can, allowed to cool to room temperature, and brokenup into lumps.

Acidic catalysts, other than sulfuric acid, may also be used, such ashydrochloric acid, oxalic acid, phosphoric acid, and the like. Theproduct is designated hereinafter as Resin I.

Epoxy resin The epoxy resins, which may be used in the presentinvention, include polyglycidyl ethers of polyhyd-ric alcohols. Theexamples given below described the preparation of these polyethers ofdifferent epoxy equivalent weights. I

Bis-phenol A was dissolved in epichlorohydrin in the proportion of 5,130parts (22.5 mols) of b-is phenol in 2,812 parts (225 mols) ofepichlorohydrin and 104 parts of water. The solution was prepared in avessel provided with heating and cooling equipment, agitator,distillation condenser, and receiver. A total of 1880 parts of solid97.5% sodium hydroxide, corresponding to 2.04 mols of sodium hydroxideper mol of bis-phenol (2% excess) was added in increments. The firstincrement of 300 parts of sodiutnhyd-roxide was added and the mixtureheated with sufficient agitation. The heating was discontinued as thetemperature reached 80 C. and cooling was started in order to remove theexothermic heat of reaction. prevented the temperature from rising tomore than 100 C. When the exothermic reaction had ceased, and thetemperature had fallen to about 97 C., a further addition of 316 partsof sodium hydroxide was made and similar further additions were effectedat successive intervals. An exothermic reaction took place after eachcaustic addition. Sufficient cooling was employed to cause. a gentledistillation of epichlorohydrin and water, but the temperature was notallowed to go below about 95 C. No cooling was necessary after the finaladdition of sodium hydroxide. After the last addition of sodiumhydroxide and with completion of the reaction, the excessepichlorohydrin was removed by vacuum distillation with use of a vesseltemperature up to about 150 C. and a pressure of about 50 mm. Hg. Aftercompletion of the distillation, the residue was cooled to about 90 C.

The temperature control, i.e., cooling,

and about 360 parts of benzene added. Continued cooling dropped thetemperature of the mixture to about 40 C. with precipitation of sodiumchloride from the solution. The sodium chloride was removed byfiltration and carefully washed with about an additional 360 parts ofbenzene to remove the polyether therefrom. The two benzene solutionswere combined and distilled to separate the benzene. When the vesseltemperature reached about 125 C., vacuum was applied and distillationcontinued until the vessel temperature was about 170 C. at 25 mm.pressure. The resulting glycidyl polyether of bis-phenol had a DurransMercury Method softening point of 9 C., an average molecular weight of370 by ebul'lioscopic measurement in ethylene dichloride, and an epoxidevalue of 0.50 epoxy equivalent per 100 grams. It had an epoxideequivalent weight of 200 and a 1,2- epoxy equivalency of 1.85. Theproduct is designated hereinafter as Resin II.

Epoxy resin-High molecular weight Epoxy resins of higher molecularweight were prepared by using smaller ratios of epichlorohydrin to hisphenol. In a vessel fitted with an agitator, 228 parts (1 mol) ofbis-phenol A and 86 parts (2.14 mols) sodium hydroxide as a 10% aqueoussolution were introduced and heated to about 45 C., whereupon 145 parts(1.57 mols) of epichlorohydrin were added rapidly while agitating themixture. The temperature of the mixture was then gradually increased andmaintained at about C. for 80 minutes. The mixture separates into atwo-phase system and the aqueous layer was drawn off from the taffy-likeproduct which formed. The latter was washed with hot water while moltenuntil the wash water was neutral to litmus. The product was then drainedand dried by heating to a final temperature of 130 C. The softeningpoint of the resulting glycidyl polyether was 65 C, The measuredmolecular Weight of the product was 630 and it had an epoxide value of0.29 epoxy equivalent per grams. The epoxide equivalent weight was 345and the 1,2-epoxy equivalency was 1.8. It is identified hereinafter asResin III.

Another glycidyl polyether was prepared in like manher to that of ResinIII, except that, for each mol of bisphenol A, there is employed 1.22mols of epichlorohydrin and 1.37 mols of sodium hydroxide. The resulting polyether had a softening point of 98 C. by Durrans Mercury Method,a molecular Weight of 1400 as measured ebullioscopically in ethylenedichloride, and an epoxide value of 0.11 epoxy equivalents per 100grams. The epoxide equivalent weight was 910 and the 1,2-epoxyequivalency was 1.54. The product is identified hereinafter as Resin 1V.

T hermohara'enable blends of phenolic resins, and epoxy resins Havingdescribed above the preparation of the resin constituents of thethermohardenable blends of the present invention, the followingexperimental results illustrate the unique performance of thehydroxyalkylated tertiary amines as catalysts for said blends.

These blends were obtained by dissolving a phenolic resin in a moltenepoxy resin at 150 C. and stirring until the mix was homogenous. Thenthe blend was cooled to C. and the catalyst was thoroughly mixed there-.in, the blend was poured into a pan, allowed to cool, and was brokeninto lumps.

the jar was turned over, orthe blend was only soft at the specifiedtemperature. Then it was necessary to cool a sample and check it. on thehot plate as described in the preceding paragraph.

The tests are summarized inthe following table:

6 tion of the'phenol by distillation, wherein the weight ratio of (A) to(B) is from about 1 to 5 to about 5 to 1; and (C) a small, catalyticallyeffective amount of N,N,N,N'- tetrakis (hydroxypropyl) ethylenediamine.

2. A stable thermohardenable resin composition comprising a blend of (A)an epoxide resin containing 1,2- epoxy groups, obtained byetherification of 4,4-dihydroxydiphenyldimethylmethane, withepichlorohydrin in an alkaline medium; (B) a fusible novolac-typephenolic resin obtained by reacting formaldehyde, in an acidic medium,with monohydric phenols having at least one hydrogenformaldehyde-reactive atom attached to the benzene ring thereof, in aratio of about 0.5 to 0.85 mol formaldehyde per 1.0 mol phenol, and,thereafter, removing at least Test Parts Epoxy Parts Parts Catalyst PotLife Shelf Life No. Resin Resin I at 130 C at 25 C.

60 None Over 4 months. None 1.5 triethanol amine Over 6 months.

60 do 6 weeks. 30 do.. 4 weeks. 30 None None 3 Quadrol 1 Over 6 months.

60 do. 14 min 4 weeks. 30 2 Quadrol 2 months. do. Over 3 months. None 3Ethomeen C/12 Over 6 months.

60 do. 2 weeks. 60 3 Ethomeen C/ 2 4 weeks. 55 3 N,N-dimethylethanolarnin 5 days. None 3 N -meta toluyl diethanol amin Over 6 months. 60 oOver 3 months. None 2 tribenzylamine 24 h Over 6 months. 60 do Over 3months. do Do.

1 Quadrol is the commercial name for N,N,N,N-tetrakis (hydroxypropyl)ethylenediamine, manufactured by Wyandotte Chemicals Corp., Wyandotte,Michigan. 2 Ethomeen is the commercial name for the compound In EthomeenS/12, R is a C1 alkyl group obtained from coconut fatty acids. InEthomeen 5/25, R is a C alkyl group obtained from soybean fatty acids.

The table demonstrates the superior characteristics of triethan-ol amineN,N,N,N'-tetrakis(hydroxypropyl) ethylenediamine, and eth oxylated fattyacid amines represented by the formula wherein R is :a straight chainalkyl group having between 12 and 18 carbon atoms, and wherein the sumof x and y is between about 2 and about 15. The compounds yield blendsof a long shelf life at room temperature, said blends being readilycurable at elevated temperatures.

Other tertiary amines are not operative, because they confer too short ashelf life or cannot be cured within a reasonable time at elevatedtemperature. For instance, blends containing dimethyl ethanolamine havea shelf life of only five days. On the other hand, N-metatoluyldiethanolamine has an acceptable shelf life, but the cure at elevatedtemperature is too slow. Other amines not listed in the table, such astriethylamine, ethylene, diamine, diethylene triamine, ethanolamine,diethanolamine, and any other amines containing primary and secondaryamine groups, were found to give an extremely short shelf life at roomtemperature.

I claim:

1. A stable thermohardenable resin composition comprising a blend of (A)an epoxide resin containing 1,2- epoxy groups, obtained by etherification of 4,4-dihydroxydiphenyldimethylmethane, with epichlorohydrin in analkaline medium; (B) a fusible novolac-type phenolic resin obtained byreacting formaldehyde in an acidic medium, with monohydric phenolshaving at least one bydnogen formaldehyde-reactive atom attached to thebenzene ring thereof, in a ratio of about 0.5 to 0.85 mol formaldehydeper 1.0 mol phenol, and, thereafter, removing at least substantialportions of the volatiles and the unreacted porsubstantial portions ofthe volatiles and the unreacted portion of the phenol by distillation,wherein the weight ratio of (A) to (B) is from about 1 to 5 to about 5to 1; and (C) a small, catalytically effective amount of ethoxyla-tedfatty acid amines represented by the formula wherein R is a straightchain alkyl group having between 12 and 18 carbon atoms and wherein thesum of x and y is between about 2 and about 15.

3. As a method of producing stable thermohardenable resin compositionswhich comprises admixing with a blend of (A) an epoxide resin containing1,2-epoxy groups obtained by etherification of4,4-dihydroxydiphenyldimethylmethane, with an epihalohydrin in analkaline medium; (B) a fusible novolac-type phenolic resin obtained byreacting formaldehyde, in an acidic medium, with a phenol which is amember of the group comprising monohydric phenols having at least onehydrogen formaldehyde-reactive atom attached to the benzene ringthereof, in a ratio of about 0.5 to 0.85 mol formaldehyde per 1.0 molphenol, and, thereafter, removing at least substantial portions of thevolatiles and the unreacted portion of the phenol by distillation,wherein the weight ratio of (A) to (B) ranges from about 1 to 10 toabout 10 to 1; a small, catalytically effective amount ofN,N,N,Ntetrakis(hydroxypropyl) ethylenediamine.

4. As a method of producing a stable thermohardenable resin composition,admixing to a blend of (A) an epoxide resin containing 1,2-epoxy groupsobtained by etherification of 4,4-dihydroxydiphenyldimethylmethane, withan epihalohydrin in an alkaline medium; (B) a fusible novolac-typephenolic resin obtained by reacting formaldehyde, in an acidic medium,with a phenol which is a member of the group comprising monohydricphenols having mol formaldehyde per 1.0 mol phenol, and, thereafter,

at least one hydrogen formaldehyde-reactive atom attached 12 and -18carbon'atoms, and wherein the sum of x and y to the benzene ringthereof, in a ratio of about 0.5 to 0.85 is between about 2 and about15.

removing at least substantial portions of the volatiles and Referencescued by theExammer 'the unreacted portion of the phenol by distillation,wherein 5 7 UNITED STATES PATENTS weight ratio of to ranges from about 1to 1 2,697,118 12/1954 Lundsted et a1. 260584 'to about 10 to 1; asmall, catalyt-ieally eifective amount of 3,200,172 8/1965 Renner260-831 ethoxylated fatty acid amlnes represented by the formula OTHERREFERENCES CH2CH2O FH 10 Lee et al.: Epoxy Resins, McGraw-Hill, N.Y.,1957 R (pp. 73-79 and 88 relied on).

\(CHRCHWFH y SAMUEL H. BLECH, Primary Examiner.

MURRAY TILLMAN, Examiner.

wherein R is a straight chain alkyl group having between 15 E, JTROJNAR, Assistant Examiner.

1. A STABLE THERMOHARDENABLE RESIN COMPOSITION COMPRISING A BLEND OF (A)AN EPOXIDE RESIN CONTAINING 1,2EPOXY GROUPS, OBTAINED BY ETHERIFICATIONOF 4,4''DIHYDROXYDIPHENYDIMETHYLMETHANE, WITH EPICHLOROHYDRIN IN ANALKALINE MEDIUM; (B) A FUSIBLE NOVOLAC-TYPE PHENOLIC RESIN OBTAINED BYREACTING FORMALDEHYDE IN AN ACIDIC MEDIUM, WITH MONOHYDRIC PHENOLSHAVING AT LEAST ONE HYDROGEN FORMALEDEHYDE-REACTIVE ATOM ATTACHED TO THEBENZENE RING THEREOF, IN A RATIO OF ABOUT 0.5 TO 0.85 MOL FORMALDEHYDEPER 1.0 MOL PHENOL, AND, THEREAFTER, REMOVING AT LEAST SUBSTANTIALPORTIONS OF THE VOLATILES AND THE UNREACTED PORTION OF THE PHENOL BYDISTILLATION, WHEREIN THE WEIGHT RATIO OF (A) TO (B) IS FROM ABOUT 1 TO5 TO ABOUT 5 TO 1; AND (C) A SMALL, CATALYTICALLY EFFECTIVE AMOUNT OFN,N,N'',N''TETRAKIS (HYDROXYPROPYL) ETHYLENEDIAMINE.
 2. A STABLETHERMOHARDENABLE RESIN COMPOSITION COMPRISING A BLEND OF (A) AN EPOXIDERESIN CONTAINING 1,2EPOXY GROUPS, OBTAINED BY ETHERIFICATION OF4,4''-DIHYDROXYDIPHENYLDIMETHYLMETHANE, WITH EPICHLOROHYDRIN IN ANALKALINE MEDIUM; (B) A FUSIBLE NOVALAC-TYPE PHENOLIC RESIN OBTAINED BYREACTING FORMALDEHYDE, IN AN ACIDIC MEDIUM, WITH MONOHYDRIC PHENOLSHAVING AT LEAST ONE HYDROGEN FORMALDEHYDE-REACTIVE ATOM ATTACHED TO THEBENZENE RING THEREOF, IN A RATIO OF ABOUT 0.5 TO 0.85 MOL FORMALDEHYDEPER 1.0 MOL PHENOL, AND, THEREAFTER, REMOVING AT LEAST SUBSTANTIALPORTIONS OF THE VOLATILES AND THE UNREACTED PORTION OF THE PHENOL BYDISTILLATION, WHEREIN THE WEIGHT RATIO OF (A) TO (B) IS FROM ABOUT 1 TO5 TO ABOUT 5 TO 1; AND (C) A SMALL, CATALYTICALLY EFFECTIVE AMOUNT OFETHOXYLATED FATTY ACID AMINES REPRESENTED BY THE FORMULA